This invention relates to actuators and more particularly to an actuator that can function in a paper making machine as either a slice lip actuator, a dilution actuator or a coatweight actuator.
A typical paper machine headbox distributes pulp slurry or stock through a long horizontal slit opening on to a perforated web or xe2x80x9cwirexe2x80x9d.
In one type of paper machine the paper density or xe2x80x9cbasis weightxe2x80x9d can be changed transverse the direction of the wire travel by opening or closing a long stainless us steel bar or xe2x80x9cslice lipxe2x80x9d which comprises the top of the slit opening. To this end there are attached to the slice lip a multiplicity of spindles or xe2x80x9cslice rodsxe2x80x9d which are equally spaced across the slice lip.
Each spindle has associated therewith an actuator, referred to hereinafter as a slice lip actuator, that imparts a linear force to its associated spindle to thereby non-permanently deform the associated portion of the slice lip. This deformation gives rise to a slit opening which in combination with all of the other nonpermanent deformations of the slice lip imparted by associated slice lip actuators yields a paper sheet having a preselected weight that is uniform across the sheet. To be effective, a slice lip actuator must deliver a force ranging from typically xc2x1500 pounds to as much as xc2x14,000 pounds. This force must be delivered in quick, precise, very small steps. At the same time, the actuator must be very small so that it can fit into and onto a multitude of headbox styles which have many and varying nearby encumbrances. Also, because downtime on a paper machine is very expensive, the slice lip actuator must be very easy to install and service.
Examples of various embodiments for prior art slice lip actuators are described in U.S. Pat. Nos. 4,892,623; 4,975,151; 5,060,539; and 5,172,600.
In another type of paper machine the basis weight profile of the web of paper is not controlled by changing the opening of the slice lip but rather by means of a series of dilution pipes or lines which extend across the width of the headbox. Water is controllably injected into the dilution lines to locally control the stock dilution thereby forming a variable consistency profile leaving the slice opening. By adjusting the amount of dilution at a plurality of points of the headbox across the machine, for example in response to a measured basis weight profile from on-line measurement, the basis weight profile of the web is controlled. This type of basis weight control is known as dilution control.
To precisely control the basis weight profile of a paper web being produced, it is apparent that the water flow in each of the dilution lines must be accurately and reliably controlled. In existing designs, this control has been performed by using conventional servo controlled ball valves, gate valves and needle valves with one valve per dilution line. Each valve has an associated actuator which will be referred to hereinafter as a dilution actuator. U.S. Pat. No. 5,549,793 describes the use of pinch valves in dilution lines of a dilution headbox of a paper making machine and shows such a valve driven by a linear motor.
In the manufacture of paper, it is often desirable to coat one or both sides of the paper web. The coating mixture is applied to the running paper web, which is typically supported on a rotating roll, and just downstream of the coating application zone, there is positioned a metering blade that controls the thickness of the coating to remain on the web. One example of a coating apparatus is disclosed in U.S. Pat. No. 4,903,632.
The purpose of the metering blade, which is often referred to as a doctor blade, is to control the thickness of the coating on the web. It is often desirable to modify the profile of the edge of the metering blade across the width of the web. A commonly utilized mechanism for doing this is a profile bar made of stainless steel and having an edge that engages a side face of the metering blade and extends the entire width of the web. Spindles having an associated actuator, referred to hereinafter as a coatweight actuator, engage the opposite edge of the profile bar at spaced apart directions along the axis of the bar and apply tensile or compressive forces to deform the bar so as to change the profile of the leading edge of the bar. This in turn deforms the metering blade so that the spacing of the metering blade edge from the surface of the web can vary across the width of the web.
A slice lip actuator or a coatweight actuator typically rotates thorough a multiplicity of turns in the actuation of its associated device. A typical dilution actuator, however, has to rotate only a xc2xc turn, that is, 90xc2x0, in order to actuate its associated valve from one end position, e.g. fully closed, to its other end position, e.g. fully open. Therefore, the actuator presently used in dilution applications is different than the actuator presently used in slice lip or coatweight applications.
It is often necessary to manually adjust all actuators. In the present design of such actuators, the manual adjustment is made through a shaft that is connected to the actuator motor shaft. This connection means that since the actuator motor shaft turns millions of times during its product life the manual shaft will also turn the same number of times thereby leading to unacceptable wear of the manual shaft seal. In the design of actuators in accordance with the prior art the motor shaft typically extends outside of the enclosure and thus a seal must be provided to ensure environmental integrity of the motor. Seals can and do wear.
Further the height of an actuator is important as a slice lip actuator must occasionally fit in tight overhead clearance such as under the torque tube connecting gross slice jacks. The typical actuator consists of the in-line arrangement of a gearbox, a motor and a sensor. This arrangement maximizes the height of the actuator. In one such arrangement, the gearbox is between the motor and the sensor and the motor and sensor are each in individual sealed housings. This arrangement not only maximizes the height of the actuator but also requires two housings to environmentally protect the actuator, thereby making sealing of the actuator more complicated and expensive.
Additionally a slice lip actuator may have to provide a much higher torque than the torque that has to be provided by a dilution actuator. Further such high torque should be provided in a small package which allows for more actuators across the slice lip and therefore better control of the slice lip.
Additionally further the sensor of the actuator should have high resolution yet the actuator must still have a small package in width and not be as high as present actuators and should be easier to assemble than present actuators.
As is described above, the present state of the art is that an actuator used for both slice lip and coatweight applications cannot be used for dilution applications and vice versa. It is, however, desirable that the same actuator be easily useable for all such applications and that the construction of the actuator be easily alterable so that an actuator used for slice lip or coatweight applications can be converted into one for dilution applications without the need for special tooling or new parts or recalibration of the position sensor that is part of the actuator.
An actuator comprising:
(a) a motor plate;
(b) a drive motor having a gear;
(c) a position sensor in side by side arrangement with the drive motor; and
(d) a speed reducer having a gear, an output shaft and a hollow input shaft for extending the output shaft; the motor plate having a first opening therein from a first side for receiving the speed reducer gear, a second opening therein from a second side opposite the first side for receiving the drive motor gear, the first and second opening each having a depth such that the drive motor gear engages the speed reducer gear; and a third opening therein for receiving the extended output shaft to thereby drive the position sensor.
An actuator comprising:
(a) a drive motor having a gear;
(b) a position sensor in side by side arrangement with the drive motor; and
(c) a speed reducer having a gear which is engaged with the drive motor gear, the speed reducer also having an output shaft and a hollow input shaft through which the output shaft is extended to thereby drive the position sensor.
An actuator comprising:
(a) a drive motor engaged with a speed reducer, the drive motor having a hollow shaft;
(b) an assembly for manually adjusting the actuator by engaging the hollow drive motor shaft, the assembly comprising:
(i) a shaft having a first end and a stub at a second end for engagement with the drive motor hollow shaft when a force is applied to the first end; and
(ii) a compression spring mounted on the stub for disengaging the shaft stub from the motor drive hollow shaft when the applied force is removed from the first end.
An actuator comprising:
(a) a drive motor having a gear;
(b) a position sensor in side by side arrangement with the drive motor;
(c) a cam disk having a first side having a predetermined shape and a second opposed side, the first side facing the position sensor, the position sensor in contact with the cam disk first side; and
(d) a speed reducer having a gear which is engaged with the drive motor gear, the speed reducer also having an output shaft and a hollow input shaft through which the output shaft is extended, the extended output shaft connected to the cam disk to thereby cause motion of the cam disk when the actuator is energized.
A cam disk for an actuator comprising:
(a) a first side that is flat; and
(b) a second side opposed to the first side, the second side having a tapered ramp thereon.
An actuator comprising:
(a) a drive motor having a gear;
(b) a position sensor in side by side arrangement with the drive motor;
(c) a cam disk having an opening therethrough and a first side having a predetermined shape and a second opposed side, the first side facing the position sensor, the position sensor in contact with the cam disk first side;
(d) a drive block having an opening, the drive block residing in the cam disk opening; and
(e) a speed reducer having a gear which is engaged with the drive motor gear, the speed reducer also having an output shaft and a hollow input shaft through which the output shaft is extended, the extended output shaft connected to the drive block opening to thereby cause motion of the cam disk when the actuator is energized.
A drive block for an actuator comprising:
(a) a first cantilever leaf spring;
(b) a second cantilever leaf spring; and
(c) an opening partway therethrough.